Question
If $$v = \frac{a}{t} + b{t^3}$$ where $$v = $$ velocity and $$t$$ is time
The dimensional formula of $$a$$ and $$b$$ are
A.
$$\left[ T \right],\left[ {{T^{ - 3}}} \right]$$
B.
$$\left[ L \right],\left[ {L{T^{ - 4}}} \right]$$
C.
$$\left[ {{T^{ - 3}}} \right],\left[ T \right]$$
D.
$$\left[ {L{T^{ - 4}}} \right],\left[ L \right]$$
Answer :
$$\left[ L \right],\left[ {L{T^{ - 4}}} \right]$$
Solution :
Dimensionally $$v = \frac{a}{t} \Rightarrow a = L{T^{ - 1}} \times T = L$$
also dimensionally $$v = b{t^3} \Rightarrow b = \frac{{L{T^{ - 1}}}}{{{T^3}}} = L{T^{ - 4}}$$